A simple virus brewed in the belly of a dead bird is set to embark on a global killing spree. The likely culprit is H5N1 - a bird flu virus with the dangerous potential to mutate into the next pandemic flu virus.
In a feature-length special, we tell the story of what could happen if a flu pandemic hits. Experts predict the next pandemic will be more disruptive than any disease we've seen before. And they're particularly worried that it will be most deadly for the young and otherwise healthy.
The last flu pandemic in 1918 killed an estimated 50 million people worldwide. Nowadays, with extensive global travel and movement, the virus will be able to spread even more easily. The estimates are that hundreds of millions could be infected and potentially die.
WATCH: Five things you need to know
